JPWO2017077895A1 - Optical fiber manufacturing method, optical fiber manufacturing apparatus, and optical fiber - Google Patents

Abstract

In the method of manufacturing the optical fiber G2 in which the drawn glass fiber G1 is coated with the ultraviolet curable resin, the optical fiber preform G is heated in the heating furnace 4 until the glass fiber G1 is drawn and wound. A cooling process for cooling the glass fiber G1 before being coated with the ultraviolet curable resin, and an ultraviolet curable primary resin is applied to the periphery of the cooled glass fiber G1, and the primary resin is surrounded before the primary resin is cured. After the primary resin and the secondary resin are applied to the primary coating step and the traveling direction of the optical fiber G2 coated with the primary resin and the secondary resin is changed by the roller 12, the secondary resin is applied. And a secondary coating step in which an ultraviolet curable resin is additionally applied and cured.

Description

  The present invention relates to an optical fiber manufacturing method, an optical fiber manufacturing apparatus, and an optical fiber.

In an optical fiber manufacturing apparatus, an increase in the speed of drawing an optical fiber is demanded by improving production technology.
Patent document 1 is an invention related to an optical fiber drawing device, and before spinning fiber that has passed through the first coating device and the curing furnace enters the second and subsequent coating devices, the spinning fiber is a fiber with high cooling efficiency. It is disclosed to draw while contacting a guide device, such as a capstan or wheel.
Patent Document 2 is an invention relating to a method of manufacturing a coated striate, and after irradiating the striate coated with resin with ultraviolet rays by the first ultraviolet irradiator, the running direction of the striate is changed, It is disclosed that the resin applied to the striate is cured to form a coating layer by irradiating the resin with ultraviolet rays by a second ultraviolet irradiation device different from the first ultraviolet irradiation device. Yes.

Japanese Laid-Open Patent Publication No. 62-24184 Japanese Unexamined Patent Publication No. 2005-162502

An optical fiber manufacturing method of the present disclosure includes:
An optical fiber manufacturing method in which a drawn glass fiber is coated with an ultraviolet curable resin,
While the optical fiber preform is heated in a heating furnace and the glass fiber is drawn and wound,
A cooling step of cooling the glass fiber before being coated with the ultraviolet curable resin;
An ultraviolet curable primary resin is applied around the cooled glass fiber, an ultraviolet curable secondary resin is applied around the primary resin before the primary resin is cured, and the primary resin and the secondary resin are applied. A primary coating process for curing
After changing the traveling direction of the optical fiber coated with the primary resin and the secondary resin with a roller, a secondary application step of additionally applying and curing an ultraviolet curable resin around the secondary resin;
Is provided.

Further, the optical fiber manufacturing apparatus of the present disclosure includes:
An optical fiber manufacturing apparatus in which a drawn optical fiber is coated with an ultraviolet curable resin,
A heating furnace that heats and softens the optical fiber preform;
A cooling device for cooling the glass fiber drawn from the softened optical fiber preform;
A primary coating device that coats an ultraviolet curable primary resin and a secondary resin around the cooled glass fiber;
A primary ultraviolet irradiation device for curing the primary resin and the secondary resin applied to the glass fiber;
A roller that changes a traveling direction of the optical fiber in which the primary resin and the secondary resin are cured;
A secondary coating device for additionally coating an ultraviolet curable resin around the optical fiber whose traveling direction is changed by the roller;
A secondary ultraviolet irradiation device that cures the resin applied by the secondary coating device.

The optical fiber of the present disclosure is
Glass fiber,
One UV-curable primary resin layer coated around the glass fiber;
A plurality of ultraviolet curable secondary resin layers coated around the primary resin layer.

It is a schematic block diagram which shows one form of the optical fiber manufacturing apparatus which can implement the manufacturing method of the optical fiber which concerns on this invention. It is a schematic block diagram of the optical fiber manufacturing apparatus which concerns on a prior art example. It is a schematic block diagram which concerns on the modification of an optical fiber manufacturing apparatus.

<Problems to be solved by the present disclosure>
In the method of cooling an optical fiber via a capstan or a wheel as in the optical fiber drawing device disclosed in Patent Document 1, it is not possible to cool uniformly in the circumferential direction of the optical fiber. Therefore, the application of the resin in the second and subsequent coating apparatuses is not uniform, and there is a possibility that uneven thickness of the resin occurs. Further, when the linear velocity is increased, the spinning fiber enters the first coating apparatus at a high temperature, and there is a limit to increasing the drawing speed.
In addition, in the method for manufacturing a coated filament disclosed in Patent Document 2, after all the ultraviolet curable resin for forming a coating layer covering the periphery of the glass fiber is applied, the resin is cured first. The first ultraviolet irradiation device and the second ultraviolet irradiation device are separately performed. That is, in order to apply the resin for forming the coating layer all at once, it is necessary to cure the resin with the first ultraviolet irradiation device to such an extent that the resin does not deform when changing the traveling direction of the optical fiber, There is a limit to speeding up the drawing, and the distance until the traveling direction of the optical fiber is changed cannot be greatly reduced.

  An object of the present disclosure is to provide an optical fiber manufacturing method, an optical fiber manufacturing apparatus, and an optical fiber capable of drawing an optical fiber at a high linear velocity without increasing the scale of an optical fiber drawing facility.

<Effects of the present disclosure>
According to the present disclosure, an optical fiber can be drawn at a high linear velocity without increasing the scale of an optical fiber drawing facility.

<Outline of Embodiment of the Present Invention>
First, an outline of an embodiment of the present invention will be described.
An optical fiber manufacturing method according to an embodiment of the present invention is as follows.
(1) A method of manufacturing an optical fiber in which a drawn glass fiber is coated with an ultraviolet curable resin,
While the optical fiber preform is heated in a heating furnace and the glass fiber is drawn and wound,
A cooling step of cooling the glass fiber before being coated with the ultraviolet curable resin;
An ultraviolet curable primary resin is applied around the cooled glass fiber, an ultraviolet curable secondary resin is applied around the primary resin before the primary resin is cured, and the primary resin and the secondary resin are applied. A primary coating process for curing
After changing the traveling direction of the optical fiber coated with the primary resin and the secondary resin with a roller, a secondary application step of additionally applying and curing an ultraviolet curable resin around the secondary resin;
Is provided.
According to the above optical fiber manufacturing method, after applying and curing a part of the resin to be finally applied around the glass fiber in the primary application step, the traveling direction of the optical fiber is changed, Thereafter, the remaining resin is applied and cured in the secondary application step. Therefore, the number of ultraviolet irradiation devices used in the primary coating process can be reduced, and a long cooling device can be arranged in an existing drawing tower. Therefore, the optical fiber can be drawn at a high linear velocity without increasing the scale of the optical fiber drawing facility.

(2) The method of additionally applying the resin in the secondary application step is a single die method in which a single resin is applied around the secondary resin applied in the primary application step with a single coating die. The resin used in the secondary application step is preferably the secondary resin.
According to the said structure, the secondary resin of the thickness provided with the intensity | strength which can endure a contact with a roller in a primary application | coating process can be apply | coated, and the remaining thickness of a secondary resin can be apply | coated in a secondary application | coating process.

(3) The method of additionally applying the resin in the secondary application step is a single die method in which a single resin is applied around the secondary resin applied in the primary application step with a single coating die. The resin used in the secondary application step is preferably different from the secondary resin.
(4) The method of additionally applying the resin in the secondary application step is a dual die method in which at least two layers of resin are applied around the secondary resin applied in the primary application step with a plurality of coating dies. It is preferable.
(5) The method of additionally applying the resin in the secondary application step includes a first additional application step of additionally applying a resin around the secondary resin applied in the primary application step, and the first additional application step. It is preferable that it is a tandem system provided with the 2nd additional application | coating process which further apply | coats resin further around the said resin apply | coated.
(6) The resin applied in the second additional application process is preferably a resin different from the secondary resin.
(7) In the secondary application step, the first-layer resin is preferably the secondary resin, and the second-layer resin is preferably a colored layer.
According to these configurations, three or more coating layers can be formed around the glass fiber.

(8) The method for manufacturing the optical fiber further includes:
A step of changing the direction of the optical fiber with a roller after the secondary coating step;
It is preferable to include a tertiary application process in which an ultraviolet curable resin is additionally applied around the resin applied in the secondary application process and cured.
According to the above configuration, it is possible to further increase the drawing speed of the optical fiber.

An optical fiber manufacturing apparatus according to an embodiment of the present invention is
(9) An optical fiber manufacturing apparatus in which a drawn optical fiber is coated with an ultraviolet curable resin,
A heating furnace that heats and softens the glass base material;
A cooling device for cooling the glass fiber drawn from the softened glass base material;
A primary coating device that coats an ultraviolet curable primary resin and a secondary resin around the cooled glass fiber;
A primary ultraviolet irradiation device for curing the primary resin and the secondary resin applied to the glass fiber;
A roller that changes a traveling direction of the optical fiber in which the primary resin and the secondary resin are cured;
A secondary coating device for additionally coating an ultraviolet curable resin around the optical fiber whose traveling direction is changed by the roller;
A secondary ultraviolet irradiation device that cures the resin applied by the secondary coating device.
According to the above optical fiber manufacturing apparatus, a part of the resin to be finally applied around the glass fiber in the primary coating apparatus is applied, and the resin is cured by the primary ultraviolet irradiation apparatus. After that, the traveling direction of the optical fiber is changed, and then the remaining resin is applied and cured in the secondary coating device and the secondary ultraviolet irradiation device. Therefore, it is possible to reduce the number of ultraviolet irradiation devices arranged directly under the heating furnace and arrange a long cooling device using an existing drawing tower. Therefore, the optical fiber can be drawn at a high linear velocity without increasing the scale of the optical fiber drawing facility.

An optical fiber according to an embodiment of the present invention is
(10) glass fiber;
One UV-curable primary resin layer coated around the glass fiber;
A plurality of ultraviolet curable secondary resin layers coated around the primary resin layer.
According to this configuration, the primary resin layer and the secondary resin layer are hardly separated from each other, and an increase in transmission loss due to the side pressure of the optical fiber is suppressed.
(11) Furthermore, it is preferable that the coating thickness of the primary resin layer and the secondary resin layer is 27.5 μm or more and less than 50 μm.

<Details of Embodiment of the Present Invention>
Hereinafter, an example of an embodiment of an optical fiber manufacturing method according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an apparatus capable of manufacturing an optical fiber by the optical fiber manufacturing method of the present embodiment.
As shown in FIG. 1, an optical fiber manufacturing apparatus 1 includes a drawing tower 2 erected in a substantially vertical direction, a heating furnace 4 provided on an upper part of the drawing tower 2 for heating an optical fiber preform G, and a glass fiber. And a cooling device 6 that cools G1. Further, the optical fiber manufacturing apparatus 1 includes a first coating application device 8, a first ultraviolet irradiation device 10, and a first guide roller 12 below the cooling device 6. Furthermore, the optical fiber manufacturing apparatus 1 includes a second guide roller 14, a second coating application device 16, a second ultraviolet irradiation device 18, a third guide roller 20, a capstan 22, A take-out bobbin 24.

  The optical fiber preform G is gripped at the upper part in the drawing tower 2, sent to the heating furnace 4, and can move in the vertical direction. The lower end side of the optical fiber preform G supplied into the heating furnace 4 is heated and melted by the heater 5 of the heating furnace 4 and is drawn downward. The optical fiber preform G is drawn downward to reduce the diameter, whereby a glass body glass fiber G1 is formed. The drawn glass fiber G1 moves along the first traveling direction d1. Note that, for example, a laser beam type outer diameter measuring device (not shown) may be provided below the heating furnace 4 so that the outer diameter of the glass fiber G1 exiting the heating furnace 4 is measured.

  A long cooling device 6 is provided below the heating furnace 4 along the first traveling direction d1. The cooling device 6 has a predetermined length L1 along the first traveling direction d1 of the glass fiber G1 in order to sufficiently cool the glass fiber G1. The cooling device 6 has an insertion hole through which the glass fiber G1 is passed in the longitudinal direction at the center position of the main body. Cooling gas is fed into the insertion hole, and the glass fiber G1 inserted through the insertion hole is cooled. In addition, the cooling device 6 has a cooling fluid passage formed along the longitudinal direction inside the main body of the cooling device 6 so that the cooling fluid circulates in the inside thereof. The cooling gas in the insertion hole is cooled by the cooling fluid, and the glass fiber G1 passes through the cooling gas atmosphere, whereby the drawn glass fiber G1 can be cooled to an appropriate temperature. Thereby, the temperature of the glass fiber G1 can be lowered to such an extent that the resin can be applied to the outer periphery.

  Below the cooling device 6 in the first traveling direction d1, a first coating application device 8 for applying an ultraviolet curable resin to the glass fiber G1 is provided. The first coating application device 8 stores a liquid ultraviolet curable resin. The first coating application device 8 is a so-called dual die type device, and includes a dual die provided with a plurality of holes coaxially as a coating die. With the dual die, two layers of ultraviolet curable resin of primary resin and secondary resin can be applied simultaneously around the glass fiber G1. The primary resin applied around the glass fiber G1 is applied, for example, with a coating diameter of 170 μm or more and 210 μm or less, preferably with a coating diameter of 200 μm. The secondary resin applied around the primary resin is made of a resin material that is harder than the resin material constituting the primary resin after curing. The secondary resin is applied with a thickness of, for example, 5 μm to 15 μm, preferably 10 μm. When the thickness of the secondary resin is 5 μm or less, it is difficult to apply the secondary resin uniformly around the primary resin, and when the thickness is 15 μm or more, it is difficult to be sufficiently cured by the first ultraviolet irradiation device 10.

  A first ultraviolet irradiation device 10 for curing the applied ultraviolet curable resin is disposed below the first coating application device 8 in the first traveling direction d1. In the present embodiment, as shown in FIG. 1, for example, three first ultraviolet irradiation devices 10 are provided. The first ultraviolet irradiation device 10 is, for example, for irradiating an optical fiber G2 coated with resin with ultraviolet rays using a multi-lamp UV lamp to cure the ultraviolet curable primary resin and secondary resin. Two layers of ultraviolet curable resin are applied to the outer periphery of the glass fiber G1 by the first coating application device 8, and then the ultraviolet curable resin is cured by the first ultraviolet irradiation device 10, whereby the glass fiber G1. An optical fiber G2 in which a primary resin coating layer and a secondary resin coating layer are formed around is manufactured. An outer diameter measuring device (not shown) is provided below the first ultraviolet irradiation device 10, and the first coating application is performed so that the outer diameter of the optical fiber G2 measured by the outer diameter measuring device becomes a predetermined value. The apparatus 8 may be configured to apply an ultraviolet curable resin.

  A first guide roller 12 is provided below the first ultraviolet irradiation device 10 in the first traveling direction d1. In the present embodiment, the pass line of the glass fiber G1 and the optical fiber G2 from the heating furnace 4 to the first guide roller 12 is a first pass line PL1. The first guide roller 12 changes the traveling direction of the optical fiber G2 that has passed through the first ultraviolet irradiation device 10 from the first traveling direction d1 to the second traveling direction d2. The second traveling direction d2 is preferably an obliquely upward direction when viewed from the lowermost part of the drawing tower 2.

  A second guide roller 14 is disposed on the downstream side of the first guide roller 12. The second guide roller 14 is provided in the vicinity of the central portion in the length direction of the drawing tower 2 so that the optical fiber G2 moves along the second traveling direction d2 different from the first traveling direction d1. Yes. And the 2nd guide roller 14 is different from the 2nd traveling direction d2 in the traveling direction of the optical fiber G2 which moved along the 2nd traveling direction d2 via the 1st guide roller 12. The travel direction is changed to d3. The third traveling direction d3 is preferably a downward direction substantially parallel to the first traveling direction d1.

Below the second guide roller 14, a second coating application device 16 for applying an ultraviolet curable resin to the optical fiber G2 is provided. The second coating and coating apparatus 16 is a so-called single die type apparatus, and includes a single die capable of coating a single layer of ultraviolet curable resin around the optical fiber G2 as a coating die. The resin applied in the second coating application device 16 can be, for example, the same resin material as the secondary resin applied in the first coating application device 8. The secondary resin applied in the second coating application device 16 is applied, for example, with a coating diameter of 230 μm or more and 260 μm or less, preferably with a coating diameter of 240 μm.
The coating diameter is not limited to 240 μm. For example, the final coating diameter may be 200 μm with a smaller diameter. In that case, in the first coating application device 8, the primary resin applied around the glass fiber G1 is applied with a coating diameter of 150 μm or more and 190 μm or less, preferably a coating diameter of 170 μm, and is applied around the primary resin. Similar to the above, the secondary resin is applied with a thickness of 5 μm to 15 μm, preferably 10 μm. Then, in the second coating application device 16, the secondary resin is applied and applied so that the final coating diameter is 180 μm or more and 220 μm or less, preferably 200 μm. In this case, the combined thickness of the primary resin and the secondary resin is 27.5 μm or more and 47.5 μm or less when the glass diameter is 125 μm.

  Further, for example, the glass diameter may be 80 μm and the final coating diameter may be 160 μm. In that case, in the first coating application device 8, the primary resin applied around the glass fiber G1 is applied with a coating diameter of 100 μm or more and 140 μm or less, preferably 120 μm, and is applied around the primary resin. Similar to the above, the secondary resin is applied with a thickness of 5 μm to 15 μm, preferably 10 μm. In the second coating application device 16, the secondary resin is applied and applied so that the final coating diameter is 140 μm or more and 180 μm or less, preferably 160 μm. In this case, the total coating thickness of the primary resin and the secondary resin is 30 μm or more and 50 μm or less when the glass diameter is 80 μm.

  Three second ultraviolet irradiation devices 18 for curing the ultraviolet curable resin additionally applied around the optical fiber G2 are provided below the second coating and coating device 16. The second ultraviolet irradiation device 18 is the same device as the first ultraviolet irradiation device 10. The UV coating resin is additionally applied to the outer periphery of the optical fiber G2 by the second coating application device 16, and then the UV curing resin is cured and reacted by the second UV irradiation device 18, whereby a coating layer is formed. The An outer diameter measuring device (not shown) is provided below the second ultraviolet irradiation device 18 so that the outer diameter of the optical fiber G2 measured by the outer diameter measuring device becomes a predetermined value. The apparatus 16 may be configured to apply an ultraviolet curable resin.

  A third guide roller 20 is provided below the second ultraviolet irradiation device 18. In the present embodiment, the pass line of the optical fiber G2 from the second guide roller 14 to the third guide roller 20 is defined as a second pass line PL2. The third guide roller 20 changes the traveling direction of the optical fiber G2 toward a capstan 22 described later. The optical fiber G <b> 2 that has passed through the second ultraviolet irradiation device 18 is drawn into the capstan 22 via the third guide roller 20, and a predetermined tension is applied by the capstan 22. By this capstan 22, the optical fiber G2 is sent further downstream. On the downstream side of the capstan 22, the optical fiber G <b> 2 is wound around the winding bobbin 24.

FIG. 2 is a schematic configuration diagram of an optical fiber manufacturing apparatus according to a conventional example.
As shown in FIG. 2, an optical fiber manufacturing apparatus 1A according to a conventional example cools a drawing tower 2, a heating furnace 4 provided on the drawing tower 2 for heating an optical fiber preform G, and a glass fiber G1. And a cooling device 6A. Furthermore, the optical fiber manufacturing apparatus 1A includes a coating application device 8, an ultraviolet irradiation device 10A, a guide roller 12A, a capstan 22, and a bobbin 24 at the lower portion of the cooling device 6A.
In the optical fiber manufacturing apparatus 1A according to the conventional example, the single coating application apparatus 8 applies the entire amount of the resin that forms the coating layer around the glass fiber G1. In order to sufficiently cure the coating layer, five ultraviolet irradiation devices 10 </ b> A are provided below the coating application device 8. Since the heating furnace 4 to the five ultraviolet irradiation devices 10A are arranged in a line in the length direction of the drawing tower 2, the length L2 of the cooling device 6A is the length of the cooling device 6 according to the present embodiment. It becomes shorter than L1.

<Example>
With respect to the optical fiber manufacturing apparatus according to the present embodiment shown in FIG. 1 and the optical fiber manufacturing apparatus according to the conventional example shown in FIG.
In each manufacturing apparatus, when evaluating the speed when drawing the optical fiber so that the optical fiber coating layer (primary resin and secondary resin) is completely cured, in the optical fiber manufacturing apparatus according to the present embodiment, Compared with the optical fiber manufacturing apparatus according to the conventional example, the drawing speed could be increased by about 10%.

  In an optical fiber manufacturing apparatus, in order to increase the speed of drawing an optical fiber, it is necessary to lengthen the cooling device in order to improve the cooling efficiency of the optical fiber. For this reason, it is conceivable to install a long cooling device with the drawing tower higher than before. However, changing the height of an existing drawing tower can be expensive and time consuming.

  On the other hand, as described above, in the present embodiment, before the optical fiber base material G is heated in the heating furnace 4 and the glass fiber G1 is drawn and wound, before the ultraviolet curable resin is coated. A cooling step for cooling the glass fiber G1, and an ultraviolet curable primary resin is applied and cured around the cooled glass fiber G1, and before the primary resin is cured, an ultraviolet curable type is provided around the primary resin. After the primary application step of applying and curing the secondary resin and the traveling direction of the optical fiber G2 coated with the primary resin and the secondary resin are changed by the guide rollers 12 and 14, an ultraviolet curable type is formed around the secondary resin. The optical fiber G2 is manufactured through a secondary coating process in which additional resin is applied and cured. According to the present embodiment, since the thickness of the resin applied in the primary application process becomes thinner than in the past, the resin applied to the optical fiber G2 in the primary application process is sufficiently cured with a small number of ultraviolet irradiation devices. Can do. Therefore, the number of first ultraviolet irradiation devices 10 arranged immediately below the heating furnace 4 and the cooling device 6 in the first pass line PL1 can be reduced as compared with the conventional case. For example, the number of ultraviolet irradiation devices arranged in the conventional example shown in FIG. 2 can be reduced to three in this embodiment. Thus, the cooling capacity can be improved by making the length L1 of the cooling device 6 longer than the length L2 of the cooling device 6A of the conventional example, without performing facility repair such as raising the drawing tower 2. Therefore, the drawing speed of the optical fiber G2 can be increased without increasing the scale of the drawing equipment for the optical fiber G2. Thus, in this embodiment, even if the glass fiber G1 and the optical fiber G2 are drawn at high speed, the resin can be applied after the glass fiber G1 and the optical fiber G2 are sufficiently cooled. Further, since the resin can be sufficiently cured with a small number of the first ultraviolet irradiation devices 10, the light for changing the traveling direction of the optical fiber G <b> 2 via the first and second guide rollers 12 and 14. The deformation of the fiber G2 can be suppressed.

  Further, in the present embodiment, the method of additionally applying the resin in the secondary application step is a method in which a single layer is provided around the secondary resin applied in the primary application step by the single coating die provided in the first coating application device 8. This is a single die method in which a secondary resin is applied. According to this configuration, the secondary resin having a thickness capable of withstanding the contact with the guide roller 12 in the primary application step is applied around the primary resin, and the remaining thickness of the secondary resin is determined in the secondary application step. By applying, a secondary resin having a finally required thickness can be applied and cured while maintaining a high linear velocity.

  The optical fiber G2 manufactured by the optical fiber manufacturing apparatus 1 of the present embodiment includes a glass fiber G1, a single ultraviolet curable primary resin layer coated around the glass fiber G1, and a primary resin layer. And a plurality of ultraviolet curable secondary resin layers coated around the periphery. Since the optical fiber G2 according to the present embodiment is configured such that only the inner side of the primary resin layer and the secondary resin layer (first secondary resin layer) is cured first, the conventional optical fiber has only one secondary resin layer. As compared with the above, a remarkable effect is obtained that the resin is hardly peeled between the primary resin layer and the secondary resin layer. That is, when the secondary resin layer is a single layer as in the prior art, when the entire primary resin layer and the secondary resin layer are cured simultaneously, the secondary resin layer is cured from the outermost part of the secondary resin layer, so that the shrinkage associated with the curing is caused. Stress tends to remain inside the primary resin layer and the secondary resin layer. On the other hand, in the primary application step, the secondary resin layer is thinly applied around the primary resin layer and the primary resin layer and the first secondary resin layer are cured, and then in the secondary application step, around the first secondary resin layer. In the present embodiment having a configuration in which the second secondary resin layer is applied and cured, the thickness of the secondary resin layer of the first layer is thinner than the conventional one, so that the secondary resin layer shrinks at the time of curing in the primary application step. Thus, stress hardly remains inside the primary resin layer and the first-layer secondary resin layer. Further, when the second secondary resin layer is cured in the secondary coating step, the primary resin layer and the first secondary resin layer are already cured, and thus are not easily affected. Therefore, it becomes difficult for stress to remain inside the primary resin layer and the secondary resin layer. Further, the first secondary resin layer is directly irradiated with ultraviolet rays by the three first ultraviolet irradiation devices 10, and then irradiated from the three second ultraviolet irradiation devices 18, and then the second secondary resin layer. Ultraviolet light that has passed through the layer is also irradiated. On the other hand, the second secondary resin layer is only directly irradiated with ultraviolet rays from the three second ultraviolet irradiation devices 18. Therefore, the first-stage secondary resin layer has a higher UV irradiation amount than the second-layer secondary resin layer. Therefore, the first secondary resin layer can be harder than the second secondary resin layer, and the conventional secondary resin layer can suppress deformation of the primary resin layer as compared to a single optical fiber. . As a result, it is possible to obtain the effect that the resin is hardly peeled off and the effect that the increase in transmission loss due to the side pressure of the optical fiber G2 is suppressed.

  While the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. In addition, the number, position, shape, and the like of the constituent members described above are not limited to the above-described embodiments, and can be changed to a number, position, shape, and the like that are suitable for carrying out the present invention.

  In the above embodiment, the resin additionally applied by the second coating application device 16 is the same as the secondary resin applied by the first coating application device 8, but is not limited to this example. The resin additionally applied by the second coating application device 16 may be different from the secondary resin, for example, a colored resin used as a color layer for identification. According to this configuration, three or more coating layers can be formed around the glass fiber in the drawing process of the optical fiber.

  Moreover, in the said embodiment, although the 2nd coating application apparatus 16 was provided with the single die, it is not restricted to this example. As the second coating / coating apparatus, a configuration including a dual die provided with a plurality of holes coaxially may be employed as in the first coating / coating apparatus 8. In such a dual-die second coating and coating apparatus, the same resin as the secondary resin can be applied as the first layer, and a resin different from the secondary resin can be applied as the second layer. As the second-layer resin, for example, a resin harder than the above-described colored resin or a secondary resin used as an outermost covering such as an optical cord can be applied. In the dual die type second coating and coating apparatus, a resin different from the secondary resin may be applied as the first layer, and a color resin for identification may be applied as the second layer.

  Further, as the second coating / coating apparatus, a so-called tandem system in which a coating apparatus that coats the first-layer resin and a coating apparatus that coats the second-layer resin may be separately provided. That is, the method of additionally applying the UV curable resin in the second coating and coating apparatus is the first additional coating in which the first resin is additionally applied and cured around the secondary resin applied by the first coating and coating apparatus. It can be set as the structure provided with the process and the 2nd additional application process which further apply | coats the 2nd layer resin around the 1st resin applied at the 1st additional application process, and hardens it. In this case, for example, the secondary resin (the remaining portion of the secondary resin applied by the first coating application device) is applied as the first layer in the first additional application step, and the secondary resin as the second layer in the second additional application step. Different colored resins can be applied. Also with this configuration, three or more coating layers can be formed around the glass fiber in the drawing process of the optical fiber.

  For example, an additional ultraviolet irradiation device may be provided between the first guide roller 12 and the second guide roller 14. Thereby, the uncured coating layer of the optical fiber G2 can be more reliably prevented.

  In the above embodiment, the first pass line PL1 directly below the heating furnace 4 and the second pass line PL2 provided on the downstream side of the first pass line PL1 are provided, but the light shown in FIG. Like the fiber manufacturing apparatus 100, it is good also as a structure further equipped with 3rd pass line PL3 in the downstream of 2nd pass line PL2. In FIG. 3, after the secondary coating step described above, a step of changing the traveling direction (orientation) of the optical fiber G2 with the guide rollers 20 and 114 and an additional UV curable resin are additionally coated by the third coating coating device 116. Then, a third application step of curing the resin by the third ultraviolet irradiation device 118 is included. According to this configuration, for example, after applying and curing a part of the resin to be finally applied around the glass fiber G1 in the primary application process and the secondary application process, the remaining part in the tertiary application process is applied. Resin can be applied and cured. Thereby, since the thickness of the resin to be cured in each of the pass lines PL1 to PL3 can be reduced, the drawing speed of the optical fiber G2 can be further increased.

  This application claims priority based on Japanese Patent Application No. 2015-216394, which is a Japanese patent application filed on November 4, 2015, and uses all the contents described in the above Japanese application.

1: Optical fiber manufacturing device 2: Drawing tower 4: Heating furnace 5: Heater 6: Cooling device 8: First coating application device 10: First ultraviolet irradiation device 12: First guide roller 14: Second guide Roller 16: Second coating and coating device 18: Second ultraviolet irradiation device 20: Third guide roller 22: Capstan 24: Winding bobbin G: Optical fiber preform G1: Glass fiber G2: Optical fiber PL1: First First pass line PL2: Second pass line PL3: Third pass line

Claims (11)

An optical fiber manufacturing method in which a drawn glass fiber is coated with an ultraviolet curable resin,
While the optical fiber preform is heated in a heating furnace and the glass fiber is drawn and wound,
A cooling step of cooling the glass fiber before being coated with the ultraviolet curable resin;
An ultraviolet curable primary resin is applied around the cooled glass fiber, an ultraviolet curable secondary resin is applied around the primary resin before the primary resin is cured, and the primary resin and the secondary resin are applied. A primary coating process for curing
After changing the traveling direction of the optical fiber coated with the primary resin and the secondary resin with a roller, a secondary application step of additionally applying and curing an ultraviolet curable resin around the secondary resin;
An optical fiber manufacturing method comprising:   The method of additionally applying the resin in the secondary application step is a single die method in which a single resin is applied around the secondary resin applied in the primary application step by a single coating die. The method of manufacturing an optical fiber according to claim 1, wherein the resin used in the next coating step is the secondary resin.   The method of additionally applying the resin in the secondary application step is a single die method in which a single resin is applied around the secondary resin applied in the primary application step by a single coating die. The method for manufacturing an optical fiber according to claim 1, wherein a resin used in a subsequent coating step is different from the secondary resin.   The method of additionally applying the resin in the secondary application step is a dual die method in which at least two layers of resin are applied around the secondary resin applied in the primary application step by a plurality of coating dies. 2. A method for producing an optical fiber according to 1.   The method of additionally applying the resin in the secondary application step is applied in the first additional application step of additionally applying a resin around the secondary resin applied in the primary application step, and the first additional application step. The method of manufacturing an optical fiber according to claim 1, wherein the method is a tandem method, further comprising a second additional application step of additionally applying a resin around the resin.   The optical fiber manufacturing method according to claim 5, wherein the resin applied in the second additional application step is a resin different from the secondary resin.   6. The method of manufacturing an optical fiber according to claim 4, wherein the first-layer resin in the secondary application step is the secondary resin, and the second-layer resin is a colored resin constituting the colored layer. . further,
A step of changing the direction of the optical fiber with a roller after the secondary coating step;
The method of manufacturing an optical fiber according to claim 1, further comprising a tertiary coating step in which an ultraviolet curable resin is additionally applied around the resin applied in the secondary coating step and cured. An optical fiber manufacturing apparatus in which a drawn glass fiber is coated with an ultraviolet curable resin,
A heating furnace that heats and softens the optical fiber preform;
A cooling device for cooling the glass fiber drawn from the softened optical fiber preform;
A primary coating device that coats an ultraviolet curable primary resin and a secondary resin around the cooled glass fiber;
A primary ultraviolet irradiation device for curing the primary resin and the secondary resin applied to the glass fiber;
A roller that changes a traveling direction of the optical fiber in which the primary resin and the secondary resin are cured;
A secondary coating device for additionally coating an ultraviolet curable resin around the optical fiber whose traveling direction is changed by the roller;
An optical fiber manufacturing apparatus, comprising: a secondary ultraviolet irradiation device that cures the resin applied by the secondary coating device. Glass fiber,
One UV-curable primary resin layer coated around the glass fiber;
An optical fiber comprising: a plurality of ultraviolet curable secondary resin layers coated around the primary resin layer.   The optical fiber according to claim 10, wherein a coating thickness of the primary resin layer and the secondary resin layer is 27.5 μm or more and less than 50 μm.

Images